Custom Resource pack not applying to player

Yes, first I tried setting the resource pack on join, but i noticed it would ask did I want to download the pack then disappear before I clicked anything.

I thought it might have something to do with the url so I tried changing it, tried a few variations, didn't change the end result though.

Next I tried creating a BukkitRunnable when a player joined to apply the resource pack to them a tick later, it worked like it should have. (Using the original url)

Can you show what you have again?